V70 D5 top coolant hose popping off
 

Hi all, I have an 05 V70 D5 AWD that last Monday decided to shed it's coolant over Tesco's car park. Upon inspection it had popped its top coolant hose and half the port the pipe connects to was missing.

Reconnected pipe, suspected rad cap, managed to get one from Euro's as it was getting late in the day.

Thought problem was cured until returned to car yesterday and it had popped again. Replaced jubilee clip as hoped it was a simple fix, but it's done it again today, except this time it's blown another piece of radiator off.

Had a cambelt and water pump done when I got it, around 6/7 months ago.

I can push the thermostat in and out, and the jiggle pin is loose. Car doesn't overheat until it pops, then slowly starts to rise and fan cuts in.

Heater matrix pipes are hot, blows hot inside.

Evidence of previous leak around thermostat housing.

No white smoke from exhaust.

No air bubbles in system, but bottom hose gets lukewarm until pipes massaged, return pipe to header tank takes forever to get hot but isn't blocked, coolant flows out of radiator if pipe disconnected from top of rad.

Are these engines common for head gasket failure? Has anybody experienced this before please?

D5 cooling systems are notoriously dull and reliable so what you have is not normal.

Before starting from stone cold, you need to remove the expansion cap to release any residual pressure then replace the expansion cap to normal tightness then start the car.
After about 10 seconds, turn off engine and undo the expansion cap. If it hisses, that's a very good indication of HG failure.
Also smell the expansion filler neck for combustible/smokey /fuel type smells.

Thanks Cheshire.

There's no hissing, coolant doesn't try and boil over if left to run then cap removed either.

My nose isn't the best at the moment but there's no untoward smell from header tank or sweet smell from exhaust.

I've even left a hammer wedged between the seat and accelerator and left it fast idling for half an hour then just left to idle, on the face of it it's behaving itself (heaters blowing nice and hot, temp gauge sat halfway) but then having a feel around the coolant hoses tells me something's not right.

They're never cold, but the hose to expansion tank and bottom hose are lukewarm, whereas top hose and matrix hoses are too hot to keep hold of.

Do the EGR coolers ever play up?

Tried the 10 second test again this morning having left the coolant cap off overnight, no pressure in system once cap removed again.

Left it fast idling and carried on burping the pipes but still no circulation, left top hose off and watched when thermostat opened while EOBD tester connected, opens at 90 degrees, temp never rises above 92.

While top hose was off blew down it, loads of air bubbles in bottom of header tank then all pipes started warming up and circulating, left fast idling and return hose now hot and steady flow of coolant back into tank, top hose shows no signs of trying to pop off the radiator and all coolant hoses are firm to squeeze but not rock solid.

Checking around the radiator a bit more there's what looks like hot glue gun residue around the top hose, so without wanting to speak too soon maybe I just had a massive air lock from where the hose has popped three times due to the bodge around the top hose?

Either that or I dislodged a block when I basically reverse flushed it?

Not sure what's happened but if the temperature is regulating correctly and hoses are staying in place, there's not much more you can do.
My guess is that some heavy handed maintenance may have created the initial problem.

So over the weekend I replaced the radiator as the top hose port really was getting close to being non existent.

Car behaved pretty much the same, didn't overheat, no air in system but not behaving as I'd expect.

Bought some coolant flush today and almost immediately once warm the expansion bottle filled with air from the return, lots of it.

Thinking possible head gasket I replaced the thermostat housing I'd already bought as a last resort, plus had seen evidence of previous leak from it.

After a bit of burping and pipe massaging car now appears to be behaving itself, no issues or air after a 30 mile run, temp never rises above 98 Deg C, so put it down to maybe thermostat housing drawing air?

However the behaviour of the car has changed in that the fan turns on and runs for around 3/4 mins after turning the key off, does anyone else's do this please?

If I park up after a drive where I've been sat in traffic for a bit then yes the fan does sometimes overrun for a few minutes

The other one is if you've been using a/c, after 20mins or so of being parked it suddenly starts running the blower for a while that's also normal

make sure the bleed hole is at the top when replaceing the thermostat. my car fan runs after being in traffic even when key is removed and the car locked its always done this its not something to worry about:regular_smile:

Thanks both for your replies.

Good to hear it's normal behaviour, just mines never done it, so probably been faulty since I've had car.

The thermostat was a complete housing as I suspected a leak/draw as there were spatters of coolant over the old belt tensioner when I bought car, even I couldn't fit that wrongly. :teeth_smile:

Checked the header tank again today, level had dropped but suspected it would due to bleeding etc.

Came home from work, engine showing warm, top hose hot, bottom lukewarm, idled at 2500rpm for 10 mins, small air bubbles in header tank again and bottom hose cold-ish even when stationary.

Any ideas please? Kind of bored of it now!

Anyone had a head off a D5 before, are there any weak spots where maybe the gasket could be gone but only drawing air into the system or a jacket rather than across a bore so letting compression in?